The present invention relates in general to stub-supported networks and pertains, more particularly, to a stub-supported coaxial microwave divider network.
Microwave divider networks such as a 2-way divider network find many applications in microwave systems. Such networks are commonly constructed in coax or stripline and have a dielectric material for supporting the center conductor. One very common network is schematically illustrated in FIG. 1 herein and employs an input port 1 along with two output ports 2 and 3 with the input port and output ports being interconnected by a 35.4 ohm quarter wavelength long transformer 5. The transformer is employed to provide a match at the input port at mid-band. In the schematic illustration of FIG. 1 each of the ports is a 50 ohm port.
Another prior art network which provides somewhat of an improvement over the one depicted in FIG. 1, is the embodiment illustrated in FIG. 2. In this arrangement there is provided a resistor 6 such as a 100 ohm resistor connected across the region where the transformer connects to ports 2 and 3. In this embodiment the transformer is split into two transmission lines 5A and 5B feeding the respective ports 3 and 2. With the divider network shown in FIG. 1, although the input port is matched, the output ports are not. Furthermore, there is a finite isolation between the output ports at mid-band. Therefore, the resistor 6 is inserted in the embodiment of FIG. 2 so as to provide a perfect output port match and isolation at mid-band.
As indicated previously, the networks illustrated in FIGS. 1 and 2 employ a dielectric material to support the center conductor which is undesirable in that this introduces additional insertion loss due to losses in the dielectric material. Furthermore, in the network of FIG. 2, the resistor is typically soldered on top of a stripline board. The presence of exposed resistive material introduces significant additional loss between the inpput and output ports.
Accordingly, one object of the present invention is to provide an improved microwave power divider network such as a 2-way divider network and which is particularly characterized by reduced insertion loss.
A further object of the present invention is to provide a microwave 2-way power divider network having increased CW power handling capability for a predetermined size network.
Still another object of the present invention is to provide a microwave 2-way power divider network with reduced input VSWR for a given size and bandwidth.